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Sirio 827 5/8wave

Discussion in 'CB Antennas' started by gmham, Jun 4, 2018.

  1. gmham

    gmham Member

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    Anyone here use the Sirio gpe27 5/8wave vertical antenna ? Have not long purchased one myself and I now notice that the tuning chart supplied seems to differ from the one available on the internet ?


    26.4 mhz = 850mm for the 5/8 wave version.
    27 mhz = 642mm
    27.185mhz = 600mm
    27.500mhz = 487mm
    28.000mhz =340mm
    28.500mhz =183mm
    29.000mhz=15mm

    The tuning table supplied with my own Sirio gpe27 5/8 wave and also available on the internet shows :

    26.700mhz = 900mm
    27.000mhz =816mm
    27.185mhz =760mm
    27.500mhz =664mm
    28.000mhz =512mm
    28.500mhz =354mm
    29.000mhz =204mm
    29.500mhz =54mm



    Very strange ?! Anyone any ideas ?!
    Thanks.john
     

  2. JAF0

    JAF0 New Member

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    Sorry but I'm done with Sirio antennas, except for repairing the BROKEN ONES people give me.
    They're just too fragile, especially the top of the NV4K!

    I just helped a friend install a new NV4K last December and even though the highest recorded wind gusts in his area were only 58mph, the top is now BENT at a 35 degree angle :( (n)

    What I've done in the past to repair this type of problem is to add a 4" long piece of solid aluminium rod that fits nicely down inside the hacksawed top tube of the NV4K and drill down into that solid aluminium rod so as to fit a 48" tuning whip from a Wilson trucker 2000. There, no more bendie bend.

    Now why didn't Sirio do that from the factory?

    I also shorten the rest of the top 2 tubes of the antenna until tuned to the correct length of approx 321".

    It's up to you how you want to secure the whip into the solid aluminium, some simply drill fairly snug, then laterally smash with a hammer, or cross-drill and use set screws.

    I like to drill the hole in the solid aluminium rod slightly under the whip diameter then use opposing heat/cold to expand the aluminium by heating it while dry-icing the (end-bevelled) whip to shrink it, plus drilling a pressure-release hole at the base of the downward-drilled hole.

    I then slam the chilled whip quickly into the heated aluminium hole in the top of the solid rod by tapping them together using (also chilled) vice-grips to hold the whip and hit the vice-grips with a hammer.

    I use nolox as both a lubricant and deoxidizer.

    After the two become one, when they slowly return to ambient temperature, they are inseparable.

    I also mark the whip at 1.25" with a permanent marker so I know the whip has fully seated.

    Y M M V!
     
    Shadetree Mechanic likes this.
  3. Shadetree Mechanic

    Shadetree Mechanic 808 On The North Side of Dover

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    Its possible that the design has changed slightly causing the tuning to be different. Sometimes manufacturers try to use as many common parts as they can between antenna models. I would use what ever came with the antenna.
    Chris 73
     
  4. Shadetree Mechanic

    Shadetree Mechanic 808 On The North Side of Dover

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    I just put up a NV4k, That is good to know. I will have to take a good look at mine when I tip it down tomorrow.
     
    JAF0 likes this.
  5. JAF0

    JAF0 New Member

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    Sorry about my rant completely forgetting to include info relevant to your post, but the top of the GPE-27 is the same silly 3mm solid aluminium rod, which bends so easily in relatively light wind, as has the NV4K. :(
     
  6. gmham

    gmham Member

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    Thanks so much guys appreciate the advice.will do as suggested and use the size given for 28.5mhz within the set off notes supplied with my antenna at time off purchase just find it strange this second set off tuning details for the same antenna.no one else running this particular vertical ?
     
  7. Shadetree Mechanic

    Shadetree Mechanic 808 On The North Side of Dover

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    If Marconi is around, he might be familiar with the variations of this antenna.
     
    gmham likes this.
  8. M0GVZ

    M0GVZ Sr. Member

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    The lengths are merely guides, a starting point to get you going. Every installation will be different.

    Everything from how high you have it above the ground, the soil conductivity, how close adjacent buildings are etc will affect the tuning of the antenna.
     
    bob85 likes this.
  9. gmham

    gmham Member

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    Okay yep totally appreciate that just wondered why Sirio had two different tuning tables for the exact same antenna ? Anyway after a conversation with Sirio in Italy last week it's seems the website has changed back to the original tuning table ie. the correct one !
     
    Shadetree Mechanic and bob85 like this.
  10. JAF0

    JAF0 New Member

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    I'd want the antenna to be precisely the correct length for the upper 18 or so feet to be right at a 1/2 wave at the target frequency, then use the supplied gamma match and tap point for tuning your unique installation.

    not that it matters much, it'll probably break off within a year or so
     
    Shadetree Mechanic likes this.

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